Mechanisms for actuating a working member of a power operated apparatus



United States Patent 1 13,.536,2;15

[72] Inventor John P. Waite [56] References Cited g Wm UNITED STATES PATENTS gm- 2,418,299 4/1947 Gorsuch 214/138 [45] patcmed on. 27 1970 2,878,950 3/1959 Wa1te 214/138 [73] Assignee .LP. Waite, Inc. Primary Examiner-Hugo O. Schulz Milwaukee, Wisconsin Attorney-Andrus, Sceales; Starke & Sawall a corporation of Wisconsin US. Cl. 214/138 E02! 3/30 FieldofSearch 214/138,

ABSTRACT: The invention relates to a mechanism for operating a working member of a power operated apparatus such as a backhoe.- The backhoe includes a boom, and a dipper stick is pivotaiiy connected to the outer end of the boom. Mounted for rotation on the boom is a rotatable member, such as a drum, and an arm is pivotally connected between the periphery of the drum and the upper end of the dipper stick. The drum is rotated by hydraulic or mechanical means, and rotation of the drum acts to move the arm to thereby pivot the dipper stick with respect to the boom.

The operating mechanism eliminates drag cables which are normally attached to the dipper and also provides increased power at all positions of the dipper stick.

MECHANISMS FOR ACTUATING A WORKING MEMBER OF A POWER OPERATED APPARATUS In the conventional backhoe, the dipper is normally actuated in the digging stroke by a cable which is attached to the forward portion of the dipper. By retrievingthe' cable, the dipper is moved toward the machine and into the material to be excavated. Problems occasionally arise with the use of the drag cable in that the cable frequently is dragged overthe rough edge of the excavation, thereby causing undue abrasion of the cable. In addition, due to the position of attachment of the cable to the dipper, it is difi'rcult to dig closely to the machine, for the cable interferes with the digging stroke. Moreover, the digging force is depended on the combined weight'of the dipper and the boom, and the cable method of actuating the drag cable tends to pull upwardly on the dipper so that the full weightof the machine is not utilized in the digging stroke.

U.S. Pat. No.- 3,319,812 of the same inventor is directed to an apparatus for operating the dipper stick of a backhoe which eliminates the use of drag cables and provides an increased digging force over that obtainable by the conventional cableoperated mechanism. The present invention constitutes an improvement to the mechanism shown in US. Pat. No. 3 ,3 l 9,8 l 2.

According to the invention, the dipper stick which carries the dipper is pivotally attached to the outer end of the boom. A rotatable member such as a drum is mounted on the boom, and an arm is pivotally connected between the outer periphery of the drum and the upper end of the dipper stick. By rotating the drum through an arc of approximately 120, a crank action is provided which acts to pivot the dipper stick with relation to the boom.

To rotate the drum, a cable is anchored on the drum and is reeved around a series of sheaves mounted on the boom. By retrieving the cable, the drum is rotated in one direction to pivot the dipper stick toward the machine, while letting out the cable, the drum is rotated in the opposite direction to pivot the dipper stick outwardlyof the machine.

With the operating mechanism of the invention, there is no drag cable or sheave system attached directly to the dipper in a position where it may interfere with the digging action of the dipper. This results in the backhoe being capable of digging closely beneath the machine and enables the dipper to undercut beneath pipes, boulders and thelike, without interference from cables. I

For a given pull on the drag cable, the digging force of the dipper can be conveniently varied by changing the number and reeving of the sheaves as well as by changing the position of the pivotal attachment of the arm to the rotatable drum. This enables the speed of digging to be varied for a given motor speed so that the motor can be driven at the most efficient speed and yet the speed of digging can be varied as desired.

As the force being applied to the dipper stick is applied to the upper end of the stick, the full weight of the machine will be utilized in the digging stroke. This is an advantage over the conventional drag cable operation in which the cable tends to pull upwardly on the dipper so that the full weight of the machine is not utilized.

The operating mechanism of the invention can be applied to existing backhoes with substantially little reconversion or alteration of the unit. Moreover, the operating mechanism can be used in conjunction with the standard dragline construction which is connected directlyto the dipper so that the operator can have his choice as to which mechanism he wishes 'to employ for a given digging operation. If the backhoe is set upto use both types of dipper operating mechanisms, in case of a malfunction of one of the mechanisms, the other mechanism can be utilized so that the down time of the machine 'is'substantially reduced or eliminated.

Other objects and advantages will appear inthe course of the following description. I

The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings: 7

FIG. 1 is a side elevation of a backhoe utilizing the dipper operating mechanism of the invention;

FIG. 2 is a fragmentary side elevation similar to FIG. 1 showing the dipper in a position beneath the boom;

FIG. 3 is a fragmentary plan view showing the connection of the arms to the drum and dipper stick; and

FIG. 4 is a diagrammatic showing of the reeving of the sheaves for the drum-operating cable.

The drawings illustrate a power operated backhoe or drag shovel comprising a cab l, which houses a drive mechanism and is mounted'for rotation on crawlers or treads 2. A boom 3 is pivotally connected between a pair of lugs 4 which extend upwardly from the forward portion of the cab 1 and a dipper stick 5 is pivotally connected to the outer end of the boom.

The lower end of the dipper stick 5 is secured to the rear edge portion of a dipper 6, and a pair of pitch braces 7 are secured together in fixed relation to positively position the dipper with respect to the dipper stick. It is contemplated, however, that in some machines a wrist action dipper may be employed in which the dipper stick is pivotally connected to the lower end of the dipper stick and can be pivoted with respect to the dipper stick by power means.

The dipper 6 of conventional construction includes a pair of side plates 8 which are connected together by a generally curved bottom 9. The lower edge of the open end of the dipper is provided with a lip 10 which carries a series of teeth 11 adapted to penetrate the material to be excavated.

To raise and lower the boom 3 with respect to the cab 1, a mast 12 extends upwardly from the cab and carries a sheave 13. Hoistline cable 14, which is wound on the drum 15, passes over the sheave 13 and is reeved over sheave 16 carried by link 17 attached to the upper end of the dipper stick, and the cable 14 is dead-ended on the mast 12. By retrieving the cable 14, sheave 16 is moved toward the sheave 13, thereby pivoting the boom 3 upwardly about the forward portion of the cab 1, while letting out the cable 14 serves to pivot the boom downwardly with respect to the cab 1.

According to the invention, the dipper stick 5 is pivoted with respect to the boom 3 by an operating mechanism including a pair of drums 18 which are located on the outside of the side surfaces of the boom 3 and are mounted for rotation on a transverse shaft 19 which extends through the boom. The inner end of an arm 20 is pivotally connected to the outer edge portion of each drum '18 by a pin 21, while the outer end of each arm is pivotally connected to the upper end of the dipper stick 5. As the drums 18 are rotated through an arc generally in the range of about 60 to 180, and preferably through an arc of approximately the arms 20 move from the position shown in FIG. 1 to the position shown in FIG. 2 to thereby pivot the upper end of the dipper stick outwardly with respect to the boom and move the dipper to a position beneath the boom. Rotating the drums 18 in the opposite direction will move the arms 20 from the position shown in FIG. 2 to the position shown in FIG. 1 to thereby pivot the dipper stick 5 and move the dipper 6 outwardly.

To rotate the drums 18, a cable 22 is anchored to each drum as indicated by 23. Each cable 22 passes over a sheave 24 mounted on boom 3 and then is dead-ended on a link 25 attached to the end of the shaft 26. Shaft 26 carries a series of sheaves 27 which are movable with respect to the boom, and a cable 28 secured to drum 29 on cab l is reeved around the sheaves 27 and around a second series of sheaves 30 carried by shaft 31. Shaft 31 is journalled on brackets 32 mounted on the boom so that the sheaves 30 are fixed with respect to the boom. The reeving of the cable 28 around the sheaves 27 and 30 is shown diagrammatically in FIG. 4.

By retrieving the cable 28, the sheaves 27 will be moved toward the fixed sheaves 30, thereby retrievingthe cables 22 and causing the drums 18 to rotate clockwise to move the dipper in toward the cab By letting out on the cable 28, the

sheaves 27 can move away from sheaves 30 and the drums 18 I can rotate counterclockwise to enable the dipper to move outwardly away from the cab.

While the drawings illustratethree, sheaves 27 and three V sheaves 30, it is contemplated that any number of sheaves can be employed depending on the power factor desired. By increasing the number of sheaves, the powerfbeing employed through the arms 20 to the dipper stick will be increased.

Thedrawing illustrate the useof a cable mechanism'for rotating the drums 18. However, it is contemplated that any other mechanical or hydraulic mechanism can be utilized for rotating or oscillating the drum. For example, a chain and sprocket drivecan be utilized, as'.well as either a hydraulic motor of hydraulic cylinder. g

,The' present invention provides afnov'el mechanism for operating the dipper stick. The drag cables which are normally attached to the dipper are relocated, and this enables the dipper to dig more closely beneath thejmachine' as there is no danger of interference with the drag cable during digging.

For agiv en pull on the operating cable 2 8 the diggingforce can be varied by changing the number and reeving of sheaves 27 and 30. This also enables the speed of digging to be varied for a given engine speed so that the engine can bedriven at the most efficient speed and yet the speed of digging may be varied as desired. Furthermore, the operating mechanism provides increased power at all positions or attitudes of the dipper stick. This is a distinctadvantage over a normal hydraulic operated unit in which the force applied to the dipper is substantially reduced when the hydraulic cylinder is at an extended position 'and the dipper is at a location beneath the boom. By properldesign of the camming action, achieved structure, a boom having one end pivotally connected to the supporting structure, a dipper stick piv'otally attached at a position intermediate of its ends to the outer portion of theboom, adipper secured to'the lower portion of the dipper stick and adapted to penetrate into the material to be excavated, a rotatable generally circular-member journalling means for journallingthe rotatablemember' for rotation on said boom, an arm having one end connected to the upper end of the dipper stick and having the opposite end connected to said rotatable member at a location spaced from the journalling means, and drive means including'a cable connected to a peripheral portion of the rotatable member for rotating said rotatable member, whereby rotation of said rotating member acts to move said armand pivot the dipper stick with respect to the boom. I

v 2. The structure of claim 1, wherein said arm is pivotably.

connected to a second peripheral portionof the rotatable member spaced from the location of, the connection of the cable to the rotatable member. 

